Method and apparatus for managing plating interruptions

ABSTRACT

A plating method and apparatus including at least one plating bath including a plating solution used for plating at least one workpiece and a source providing a first current, wherein the first current is supplied to the plating solution when plating the at least one workpiece, and providing a second current, lower than the first current, wherein the second current is supplied to the plating solution during an interruption. The plating method and apparatus may include at least one main bath, at least one main anode, at least one auxiliary bath, at least one auxiliary anode, and/or a conveying unit. A portion of the conveying unit or the at least one workpiece may act as a cathode or anode. The plating method and apparatus may continuously expose a workpiece to a plating solution.

BACKGROUND OF THE INVENTION

[0001] This application claims the priority of Korean Patent Application No. 2003-41445, filed on Jun. 25, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

[0002] 1. Field of the Invention

[0003] The present invention relates to a method and apparatus for plating an integrated circuit device, and more particularly, to a method and apparatus for plating an integrated circuit device, by reducing an electrical plating current when an interruption in plating occurs.

[0004] 2. Description of the Related Art

[0005] A process of plating a semiconductor lead with a layer of metal (or other material) is carried out when fabricating an integrated circuit device, such as a semiconductor device. The plating process is usually based on an electroplating technology in which tin is layered onto a lead. In Korean Patent Publication No. 2001-0015412 filed on Jul. 22, 2000, entitled “A Plating Apparatus and Method for Preventing Substitution and Precipitation” a conventional plating method employing electroplating technology is described to plate workpieces with a metal alloy.

[0006] A plating process for a semiconductor device is performed through a continuous plating procedure according to demands for fabricating semiconductor devices in large quantities. While semiconductor workpieces, which are the portion of the semiconductor device that requires plating, are placed onto a conveying unit, and are continuously conveyed, a layer of metal including tin may be coated onto the lead of the semiconductor workpieces. In a conventional example, a plating apparatus includes a plurality of plating baths aligned for performing the plating function. The plating process is performed by passing the semiconductor workpieces through the plating baths, while they are disposed on a conveying unit.

[0007] The plating apparatus may further include a plurality of preprocessing baths, such as chemical deflashing, rinsing, descaling, and/or activating baths, and/or rinsing baths respectively interposed between the preprocessing baths which are aligned next to the plating baths. Furthermore, the plating apparatus may include rinsing baths, neutralizing baths, and/or a drier disposed after the plating baths. All the solution baths and plating baths may be aligned, and thus, allow the semiconductor workpieces hung from a chain belt of the conveying unit to pass therethrough, thereby performing a plating process.

[0008] When the plating process is performed by a continuous plating procedure, undesirable situations may occur. For example, when the plating process stops due to an error, for example, generated in the plating apparatus, the semiconductor workpieces may not be conveyed for a duration of time. During this time, some semiconductor workpieces which are dipped in the plating baths may be subjected to over-plating. To avoid over-plating, most plating apparatuses which use electroplating technology are configured to cut off a current supply to anodes of the plating baths when the plating process has stopped, namely, when the semiconductor workpieces do not move due to an interruption in the plating process.

[0009] However, if the current supply is cut off, a semiconductor workpiece may be poorly plated. For example, in the case of lead free plating, a solution supplied to tin plating baths contains bismuth (Bi). Bi has a strong metal substitution property such that when current being supplied to the anode(s) is cut off, the bismuth Bi will bond to the lead of the semiconductor workpieces and accordingly, the lead being plated will become oxidized. In addition, since the lead of the semiconductor workpieces interposed between the plating baths is exposed to air, the lead of the semiconductor workpieces may become oxidized due to air exposure.

[0010] For example, during a conventional plating process, about 30 semiconductor workpieces are interposed in the plating baths at one time. In the case of an interruption, all 30 semiconductor workpieces may become oxidized or overplated and thus, must be re-plated. During the re-plating process, portions of lead which are undesirably plated or oxidized should be stripped and then rinsed and plated again, thereby adversely affecting the entire plating process.

SUMMARY OF THE INVENTION

[0011] Exemplary embodiments of the present invention provide a method and apparatus for plating, which can reduce the errors associated with workpieces being poorly plated, underplated, and/or overplated.

[0012] Exemplary embodiments of the present invention provide a method and apparatus for plating, which reduce undesirable results that may occur from interruptions in the plating process.

[0013] Exemplary embodiments of the present invention provide a method and apparatus for plating, which can improve the effective yield of a process of semiconductor fabrication.

[0014] Exemplary embodiments of the present invention provide a method and apparatus for plating, which plates at least one workpiece by passing the at least one workpiece through at least one plating bath and decreases an electrical current supplied to the at least one workpiece during interruptions in the plating process.

[0015] Exemplary embodiments of the present invention provide a method and apparatus for plating, which decrease the applied current during an interruption such that the current is low enough to not induce plating and high enough so as to not induce at least one of substitution and precipitation of elements in the plating solution.

[0016] Exemplary embodiments of the present invention provide a method and apparatus for plating, which plates at least one workpiece by passing the at least one workpiece through at least one main plating bath and at least one auxiliary plating bath and decreases an electrical current supplied to the at least one workpiece during interruptions in the plating process.

[0017] Exemplary embodiments of the present invention provide an apparatus for plating including at least one plating bath including a plating solution used for plating at least one workpiece and a source providing a first current, wherein the first current is supplied to the plating solution when plating the at least one workpiece, and providing a second current, lower than the first current, wherein the second current is supplied to the plating solution during an interruption.

[0018] Exemplary embodiments of the present invention provide a method including plating at least one workpiece by passing the at least one workpiece through at least one plating bath and changing a first current to a second current during an interruption in the plating.

[0019] Exemplary embodiments of the present invention provide an apparatus including at least one main plating bath and at least one auxiliary plating bath, arranged such that a plating solution may flow from the at least one main plating bath into the at least one auxiliary plating bath, wherein at least one workpiece plated by the apparatus is not exposed to the environment outside of the plating bath solution.

[0020] Exemplary embodiments of the present invention provide a method including providing at least one plating bath and at least one auxiliary bath such that a plating solution may flow from the at least one main plating bath into the at least one auxiliary plating bath and passing at least one workpiece through the at least one main plating bath and the at least one auxiliary plating bath such that the at least one workpiece is not exposed to the environment outside of the plating solution.

[0021] Exemplary embodiments of the present invention provide an apparatus including at least one main plating bath, at least one auxiliary plating bath, arranged such that a plating solution, with a current applied thereto, may flow from the at least one main plating bath into the at least one auxiliary plating bath, and a conveying unit for providing at least one workpiece to the plating solution with the current applied thereto, at least a portion of the conveying unit or the at least one workpiece acting as one of a cathode and anode to conduct the current.

[0022] Exemplary embodiments of the present invention provide a method including passing at least one workpiece though at least one plating bath and at least one auxiliary bath arranged such that a plating solution, with a current applied thereto, may flow from the at least one main plating bath into the at least one auxiliary plating bath and conducting the current using at least a portion of the conveying unit or the at least one workpiece as one of a cathode and anode.

[0023] Exemplary embodiments of the present invention supply a current between 5% and 40% of the original electrical plating current before the interruption.

[0024] Exemplary embodiments of the present invention utilize a plating solution containing tin and bismuth, such that a tin-bismuth layer is formed on the workpieces during the plating process.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other examples and exemplary embodiments of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

[0026]FIG. 1 is a flow chart illustrating a plating method according to an exemplary embodiment of the present invention;

[0027]FIG. 2 is a schematic diagram of a plating apparatus according to an exemplary embodiment of the present invention;

[0028]FIG. 3 is an exemplary schematic view of main plating baths and auxiliary plating baths comprised in the plating apparatus of FIG. 2;

[0029]FIG. 4 is an exemplary schematic view illustrating electrodes installed in the main plating baths and the auxiliary plating baths comprised in the plating apparatus of FIG. 3;

[0030]FIG. 5A is an exemplary schematic sectional view illustrating a state in which current is supplied to the main plating baths of FIG. 3;

[0031]FIG. 5B is an exemplary schematic sectional view illustrating a state in which current is supplied to the auxiliary plating baths of FIG. 3;

[0032]FIG. 6A is an exemplary perspective view of the auxiliary plating bath of FIG. 3; and

[0033]FIG. 6B is an exemplary side view of the auxiliary plating bath of FIG. 3.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE INVENTION

[0034] Exemplary embodiments of the present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.

[0035] According to an exemplary embodiment of the present invention, a plurality of plating baths are aligned and workpieces are conveyed by a chain belt 500 or other conveying unit. When a plating apparatus stops or an interruption in plating occurs, possibly due to an error in the plating apparatus, current supplied from a power supply and through anodes in a plating solution held in the plating baths is reduced. The reduction in current may be a amount sufficient to avoid undesirable results that may occur from the workpieces being overexposed during the plating process.

[0036] Moreover, in addition to the current reduction process, the plating process may include auxiliary plating baths interposed between the main plating baths to help keep the workpieces from being oxidized, even when the plating process stops. The auxiliary plating baths, which also contain the plating solution, help manage the workpieces' exposure to the plating solution contained in both the main and auxiliary plating baths. Further, the plating apparatus employs auxiliary anodes in the auxiliary plating baths, such that when the plating process stops, an amount of current to avoid a metal substitution reaction is supplied through the auxiliary anodes to the plating solution.

[0037] According to an exemplary embodiment of the present invention, even though the plating apparatus or the conveying unit may stop, thereby interrupting the plating process, causing poor plating, such as metal substitution, precipitation, over-plating and oxidation of the workpieces due to their exposure to metals, that may be in the plating solution and air can be reduced. As a result, the workpieces being plated can avoid poor plating and over-plating by reducing the amount of current being provided to the plating solution at the time the interruption occurs

[0038]FIG. 1 is a flow chart illustrating a plating method according to an exemplary embodiment of the present invention. FIGS. 2 through 6B are schematic diagrams illustrating a plating apparatus according to an exemplary embodiment of the present invention.

[0039] Referring to FIG. 1, when a plating process stops, for example, due to an error, an electrical plating current supplied to a plating solution held in the plating baths is decreased. Workpieces, for example, leads of integrated circuit devices being plated in the plating baths, may be able to avoid undesirable metal substitution that may occur from the duration of exposure incurred from the interruption in the plating process.

[0040] In an exemplary embodiment of the present invention, for example, in the case of lead free tin-bismuth plating, when the plating process stops due to an interruption in the plating apparatus, current supplied to the workpieces immersed in the plating baths may be cut off. If a plating current is continuously supplied, the workpieces conveyed by a conveying unit, will be continuously immersed in the plating solution. Consequently, since the plating reaction is continuously performed on the workpieces, a plating layer, composed of the metal contained in the plating solution, might become thicker than required. To avoid such over-plating, the plating current may be reduced when the plating process stops.

[0041] An exemplary embodiment of the present invention provides for decreasing the plating current supplied to the plating solution in the plating baths when the plating process stops to avoid substitution and/or precipitation from occurring. The substitution and/or precipitation occur from prolonged exposure elements in the plating solution, for example, bismuth.

[0042] In an exemplary embodiment of the present invention, during an interruption in the plating the process, the plating current may be reduced to a level sufficient to avoid plating, in addition to substitution and/or precipitation. The level of the current should be high enough to avoid substitution and/or precipitation but low enough to not induce plating.

[0043] In an exemplary embodiment of the present invention, the plating current is approximately between 75 A to 100 A during normal operation, and the plating current used to avoid metal substitution and precipitation is approximately between 5 A to 30 A. Thus the plating current needs to be decreased to a level between 5% to 40% of the plating current during normal operation. In an exemplary embodiment the plating current is decreased to approximately 15 A when the plating current was originally, for example approximately 75 A.

[0044] In an exemplary embodiment of the present invention a plating procedure is performed by sequentially conveying workpieces in a plating apparatus in which plating baths are aligned. Solution baths are disposed at front and rear sides of the plating baths. This example is be explained below in detail.

[0045]FIG. 2 is a schematic diagram of a plating apparatus according to an exemplary embodiment of the present invention. FIG. 3 is a schematic diagram of plating baths and auxiliary plating baths of the plating apparatus in FIG. 2.

[0046] Referring to FIG. 2, the plating apparatus includes a plurality of plating baths 300 which are aligned, and a plurality of solution baths 250 aligned before and after the plating baths 300. Lead frames composed of packaged workpieces, for example, semiconductor workpieces, are sequentially and continuously conveyed to the plating baths 300 and the solution baths 250 by a conveying unit, such that the workpieces are attached to the conveying unit, so as to be plated by being immersed in the plating bath solution of the plating baths 300.

[0047] The workpieces may be attached to the conveying unit at a load point 210 and then input into the plating apparatus. The workpieces may be first chemically deflashed, rinsed, high-pressure rinsed, and/or descaled. The workpieces may be rinsed again, activated, by being dipped in a solution containing an activator, and/or pre-dipped in a pre-processing bath 290. The workpieces may then be conveyed to the plating baths 300 to be plated. The workpieces may then continue on to the rest of the solution baths to be neutralized, hot rinsed, air rinsed, and/or dried. The workpieces may be removed from the plating apparatus at an unload point 230. It is appreciated that a plating process is performed when the workpieces pass through the plating baths 300.

[0048] Referring to FIG. 3, the plating baths 300 include a plurality of main plating baths, for example, four (although there may be another number) main plating baths, 310, 320, 330, and 340 and a plurality of auxiliary plating baths, for example, three (although there may be another number, but generally one less than the number of main plating baths) auxiliary plating baths 400,410, and 420. The auxiliary plating baths 400, 410, and 420 pass through connection parts 350 which interconnect the main plating baths 310, 320,330, and 340. Thus, the auxiliary plating baths 400, 410, and 420 allow a plating solution to flow in spaces between the main plating baths 310, 320, 330, and 340. That is to say, the auxiliary plating baths 400, 410, and 420 are interconnected between the main plating baths 310, 320, 330, and 340 in order to allow the plating solution to flow through as well, so that the workpieces conveyed by the chain belt 500, which are dipped in the plating solution, are not separated from the plating solution and are therefore not exposed to air, in the spaces between the main plating baths 310, 320, 330, 340. Accordingly, the plating solution provided to the main plating baths 310, 320, 330, and 340 can also flow into the auxiliary plating baths 400, 410, and 420.

[0049] Referring to FIG. 1, in step 110, the main plating baths 310, 320,330, and 340 and the auxiliary plating baths 400, 410, and 420 are aligned. In step 120, the workpieces are continuously conveyed to the plating baths to be plated. A plating current is supplied to the workpieces and anodes 700 in the main plating baths 310, 320, 330, and 340 through a power source 600 to plate the workpieces. In an exemplary embodiment of the present invention, the plating current may range from 75 A to 100 A and is supplied by the power source 600 which may comprise a rectifier to induce the plating reaction.

[0050] In step 130, the plating current is applied to the anodes 700 which may be flat panels, and which are disposed in each of the main plating baths 310, 320, 330, and 340. The workpieces, attached to the conveying unit are electrically connected thereto, and thus contact the power source 600. As a result, either the workpieces or the conveying unit may act as a cathode.

[0051] Metal contained in the plating solution is bonded to the workpieces during the plating process, with the electrical current produced by the plating current. In an exemplary embodiment of the present invention, lead-free tin-plating is used. The lead-free tin-plating may be accomplished by plating the workpieces in a plating solution containing tin and bismuth. The tin and bismuth may be plated on the workpieces at any desired atomic ratio by the plating current.

[0052] The plating process may stop or an interruption may occur for various reasons during the plating process. Upon interruption, the chain belt does not operate, such that the workpieces remain immersed in the plating solution for the duration of the interruption.

[0053] If the workpieces continue to be immersed in the plating solution while the normal amount of current is supplied, over-plating may occur on the workpieces, which is undesirable. In step 130 of FIG. 1, when the plating process stops or an interruption occurs, the power source 600 will be decreased to decrease the plating current supplied to the workpieces through the anodes 700.

[0054] In an exemplary embodiment of the present invention, the plating current automatically decreases in response to a program which is set by an controller (not shown), when the plating process stops or is interrupted. The program would modify the plating process by adjusting the amount of current being supplied to the workpieces in the event of an interruption. The resulting plating current will be reduced, by the program to a rate which is approximately 5% to 40% of the original plating current used during the normal operation.

[0055] The plating current is decreased to avoid over-plating the workpieces, which remain in the plating solution. Such over-plating may result in the workpieces acquiring a plating layer which is excessively thick. Since the plating current is a factor in determining the thickness of the plating layer through the plating reaction, the plating reaction can be substantially reduced by reducing the plating current.

[0056] If metals, for example, bismuth, which have a strong metal substitution property, are present in the plating solution, as in the case of the lead free tin-plating, when no plating current is applied, substitution and/or precipitation can occur on the workpieces.

[0057] However, if instead of no current, a lower ampere rating plating current is supplied through the anodes 700 than in the normal operation, then the bismuth may be substantially prevented from being substituted, precipitated and/or bonded onto the workpieces.

[0058] As shown in FIG. 3, the anodes 700 in the main plating baths 310, 320, 330, and 340 are not extended into the auxiliary plating baths 400, 410, and 420. Thus, when the plating process stops, the workpieces positioned in the auxiliary plating baths 400, 410, and 420, that is, in the connection parts 350 between the main plating baths 310, 320, 330, and 340 may suffer from an unbalanced composition ratio of tin-bismuth.

[0059] Referring to FIGS. 4, 5A and 5B, auxiliary anodes 750, which may be flat panels, are located within the auxiliary plating baths 400, 410, and 420. FIG. 4 is an exemplary schematic plan view illustrating electrodes in the main plating baths 310, 320, 330, and 340 and the auxiliary plating baths 400. FIG. 5A is an exemplary schematic sectional view illustrating a state in which current is applied to the main plating baths 310, 320, 330, and 340. FIG. 5B is a schematic sectional view illustrating a state in which current is applied to the auxiliary plating baths 400, 410, and 420.

[0060] Referring to FIG. 4, the auxiliary plating bath 400 passes through the connection part 350 to interconnect the main plating baths 310 320. Referring to FIG. 3, since the area of the first main plating bath 310 is divided by a plating solution partition 311, the plating solution in the first main plating bath 310 is held within the plating solution partition 311. The plating solution partition 311 allows a drain (not shown) for discharging the plating solution to be disposed between the plating solution partition 311 and the wall of the main plating bath 310.

[0061] The auxiliary plating bath 400 extends to the area of the main plating bath 310, which holds the plating solution such that the plating solution can flow into the auxiliary plating bath 400. Therefore, as shown in FIGS. 5A and 5B, when the plating process stops and the chain belt 500 does not move, the workpieces 550, which are not immersed in the main plating bath 310 or 320, are positioned and halted inside the auxiliary plating baths 400, 410, and 420 and thus, continue to be immersed in the plating solution 390 in the auxiliary plating baths 400, 410, and 420.

[0062] The auxiliary anodes 750 are located inside the auxiliary baths 400, 410, and 420. The auxiliary anodes 750 may have a flat panel shape and may be the same length as the auxiliary plating baths 400, 410, and 420. The auxiliary anodes 750 may be used to provide a continuous movement of the workpieces being passed through the plating solution, and to avoid metals which have strong metal substitution and/or precipitation properties, such as BI, from bonding to the workpieces 550, which are immersed in the auxiliary plating baths 400, 410, and 420. Thus, the auxiliary anodes 750 can be connected to the power source 600 together with the main anodes 700 disposed inside the first main plating bath 310. Accordingly, when the plating process stops, a plating current which is less than the plating current supplied during normal operation is provided to the auxiliary anodes 750 as well as the main anodes 700. In another exemplary embodiment, the main anodes 700 may be extended inside the auxiliary plating baths 400, 410, and 420 to perform the same function as the auxiliary anodes 750, either to replace or augment the function of the auxiliary anodes 750.

[0063] Since the auxiliary anodes 750 are disposed in the auxiliary plating baths 400, 410, and 420, protection of the workpieces from substitution and/or precipitation can be continuously provided, even during an interruption in the plating process.

[0064] During the operation of plating the workpieces, as shown in FIG. 5B, as the plating solution 390 is also contained in the auxiliary plating baths 400, 410, and 420, the workpieces 550 can be continuously conveyed while being immersed in the plating solution 390 during the series of plating processes described with reference to FIG. 2. Therefore, in an exemplary embodiment, even though the plating process stops, the workpieces 550 need not be exposed to air, thereby reducing or avoiding oxidation due to exposure to air.

[0065] Furthermore, since the auxiliary plating baths 400, 410, and 420 allow the plating solution 390 to pass through the separate plating baths 310, 320, 330, and 340, the auxiliary plating baths 400, 410, and 420 can achieve the same plating effect as when a regular plating bath, for example, 310 is used. That is to say, plating uniformity may be improved by virtue of the introduction of the separate main plating baths 310, 320, 330, and 340 an/or the auxiliary plating baths 400, 410, and 420.

[0066] If the auxiliary plating baths 400, 410, and 420 are not used, no plating is actually carried out between the main plating baths 310, 320, 330, and 340. By introducing the auxiliary plating baths 400, workpieces 550 can be continuously plated while being conveyed and problems caused as a result of the main plating baths 310, 320, 330, and 340 being separated in the plating apparatus can be solved.

[0067] In fact, since each of the main plating baths 310, 320, 330, and 340 has a length of about 1.5 meters, the entire plating bath 300 is longer than 6 meters. Practically, it is not sound to construct one single plating bath at this length. The plating apparatus according to an exemplary embodiment of the present invention has substantially the same effect as a single plating bath by employing the auxiliary plating baths 400, 410, and 420.

[0068] The auxiliary plating baths 400, 410, and 420 are constructed as shown in FIGS. 6A and 6B. FIGS. 6A and 6B are respectively a perspective view and a side view of one of the auxiliary plating baths 400.

[0069] Referring to FIGS. 6A and 6B, the auxiliary plating bath 400 may be constructed to have a bottom plate 420 and two walls 410 which may have a flat panel shape and are perpendicularly attached to bottom plate 420 supported by legs 430. The walls 410 may be supported on the bottom plate 420 by supports 460. A hole 440 may be formed in one of the walls 410, and a sensor 470 may be inserted into the hole 440 to detect whether or not the plating solution exists.

[0070] The walls 410 of the auxiliary plating bath 400 may be long enough for the auxiliary plating bath 400 to reach at least the plating solution held in the main plating baths 310 and 320 when the auxiliary plating bath 400 is interposed between the main plating baths 310 and 320 as shown in FIG. 4. In an exemplary embodiment of the present invention, the walls 410 of the auxiliary plating bath 400 are sufficiently long to allow the auxiliary plating bath 400 to pass beyond and/or contact the plating solution partition 311.

[0071] Referring to FIG. 1, after the interruption in the plating process is resolved, the plating current may be increased back up to a level sufficient for plating according to normal operation, and is supplied to the main anodes 700 or the auxiliary anodes 750 to resume the plating process. Poor plating such as over-plating, metal substitution and/or precipitation can be avoided during interruption periods. Less reworking of the workpieces that have been subjected to poor plating is, therefore, required.

[0072] As described above, even though a plating process stops or an interruption occurs, the exemplary embodiments of the present invention can effectively maintain workpieces, for example, lead frames, so they are properly plated. Accordingly, reworking is reduced, leading to improved productivity and rate of operation of the plating apparatus.

[0073] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 

What is claimed is:
 1. A plating method comprising: immersing at least one workpiece in a plating solution held in at east one plating bath; supplying a plating current to at least one anode in the plating solution to plate the at least one workpiece; decreasing the plating current supplied to the at least one anode upon interruption of the plating; and returning the plating current a previous amount after the interruption has ended to resume plating.
 2. The plating method of claim 1, wherein, the plating current is decreased to 5% to 40% of an original value.
 3. The plating method of claim 1, wherein the plating solution includes tin and bismuth and a tin-bismuth layer is plated on the at least one workpiece.
 4. A plating apparatus comprising: a plurality of main plating baths which are aligned and each holding a plating solution; a plurality of anodes in the plating solution of the plurality of main plating baths; a plurality of auxiliary plating baths interconnected between the plurality of main plating baths for allowing the plating solution to flow therethrough; a conveying unit, which sequentially conveys workpieces to the plurality of main plating baths and the plurality of auxiliary plating baths to be plated; and a power source for selectively supplying a plating current to the plurality of anodes which is reduced when the plating is interrupted.
 5. The plating apparatus of claim 4, further comprising a plurality of auxiliary anodes connected to the power source and disposed in the plurality of auxiliary plating baths.
 6. The plating apparatus of claim 5, wherein the plurality of auxiliary anodes are commonly connected to the plurality of anodes which are connected to the power source.
 7. The plating apparatus of claim 4, wherein each of the plurality of auxiliary anodes extends into a corresponding one of the plurality of auxiliary plating baths.
 8. The plating apparatus of claim 4, further comprising a plurality of sensors, each inserted into one of the plurality of auxiliary plating baths for sensing the plating solution flowing into the plurality of auxiliary plating baths.
 9. The plating apparatus of claim 4, wherein the plating current is decreased to 5% to 40% of an original value.
 10. A plating method of using a plating apparatus, which includes a plurality of main plating baths aligned for holding a plating solution, a plurality of anodes in the plating solution of the plurality of main plating baths, a plurality of auxiliary plating baths interconnected between the plurality of main plating baths for allowing the plating solution to flow therethrough, a conveying unit acting as a cathode to the plurality of anodes for sequentially conveying workpieces to the plurality of main plating baths and the plurality of auxiliary plating baths, and a power source for applying current to the plurality of anodes, the plating method comprising: sequentially and continuously supplying the workpieces to the plating apparatus, which includes using the conveying unit, to pass the workpieces through the plurality of main plating baths and the plurality of auxiliary plating baths; supplying a plating current provided by the power source to the plurality of anodes to plate the workpieces; reducing the plating current supplied by the power source upon interruption of the plating; and returning the plating current to a previous amount after the interruption has ended to resume plating.
 11. The plating method of claim 10, wherein the plating solution includes tin and bismuth, and a tin-bismuth layer is plated on the workpieces.
 12. The plating method of claim 10, wherein, the plating current is decreased to 5 to 40% of an original value.
 13. The plating method of claim 10, wherein the plating apparatus further includes a plurality of auxiliary anodes disposed inside the plurality of auxiliary plating baths, and the plating current supplied by the power source when an interruption occurs is applied both to the plurality of anodes and the plurality of auxiliary anodes.
 14. The plating method of claim 13, wherein the plating apparatus further includes a plurality of auxiliary anodes, each of the plurality of auxiliary anodes extending into a corresponding one of the plurality of auxiliary plating baths, and the plating current supplied by the power source is applied both to the plurality of anodes and the plurality of auxiliary anodes.
 15. An apparatus comprising: at least one plating bath including a plating solution used for plating at least one workpiece; and a source providing a first current, wherein the first current is supplied to the plating solution when plating the at least one workpiece, and providing a second current, lower than the first current, wherein the second current is supplied to the plating solution during an interruption.
 16. The apparatus of claim 15, wherein the source provides the first current after the interruption has ended.
 17. The apparatus of claim 15, wherein the plating solution includes tin and bismuth and a tin-bismuth layer is plated on the at least one workpiece.
 18. The apparatus of claim 15, wherein the second current is 5% to 40% of the first current.
 19. The apparatus of claim 15, wherein the second current is low enough to not induce plating and high enough so as to not induce at least one of substitution and precipitation of elements in the plating solution.
 20. A method comprising: plating at least one workpiece by passing the at least one workpiece through at least one plating bath; and changing a first current to a second current during an interruption in the plating.
 21. The method of claim 20, further comprising: increasing the second current to the first current after the interruption has ended.
 22. The method of claim 20, wherein the plating further includes submerging the at least one workpiece in the plating solution, and exposing the first current to the workpiece in the plating solution.
 23. The method of claim 22, wherein the plating solution includes tin and bismuth and the plating forms a tin-bismuth layer on the at least one workpiece.
 24. The method of claim 20, wherein the second current is 5% to 40% of the first current.
 25. The method of claim 20, wherein the second current is low enough to not induce plating and high enough so as to not induce at least one of substitution and precipitation of elements in the plating solution.
 26. An apparatus comprising: at least one main plating bath; and at least one auxiliary plating bath, arranged such that a plating solution may flow from the at least one main plating bath into the at least one auxiliary plating bath, wherein at least one workpiece plated by the apparatus is not exposed to the environment outside of the plating bath solution.
 27. A method comprising: providing at least one plating bath and at least one auxiliary bath such that a plating solution may flow from the at least one main plating bath into the at least one auxiliary plating bath; and passing at least one workpiece through the at least one main plating bath and the at least one auxiliary plating bath such that the at least one workpiece is not exposed to the environment outside of the plating solution.
 28. An apparatus comprising: at least one main plating bath; at least one auxiliary plating bath, arranged such that a plating solution, with a current applied thereto, may flow from the at least one main plating bath into the at least one auxiliary plating bath; and a conveying unit for providing at least one workpiece to the plating solution with the current applied thereto, at least a portion of the conveying unit or the at least one workpiece acting as one of a cathode and anode to conduct the current.
 29. A method comprising: passing at least one workpiece though at least one plating bath and at least one auxiliary bath arranged such that a plating solution, with a current applied thereto, may flow from the at least one main plating bath into the at least one auxiliary plating bath; and conducting the current using at least a portion of the conveying unit or the at least one workpiece as one of a cathode and anode. 